The Hindi script is a subset of the Devanagari script which in turn evolved from the ancient Brahmi script (FIG. 7). Other Indian languages using the Devanagari script include Marathi and Sanskrit. Other scripts derived from Brahmi include: Gujarathi, Oriya, Punjabi (also called Gurmukhi); Bengali, Assamese, Telugu, Tamil, Kannada, Malayalam (India); Sinhala (Sri Lanka); Nepali (Nepal-derived from Devanagari); Burmese (Myanmar—Burma); Tibetan (Tibet); Laotian (Laos); Thai (Thailand); Khmer (Cambodia); Java, Bali, Batak, Bugis/Buginese (Indonesia); and Tagalog (Philippines)
Hindi is the official language of India. Most Indian school children are required to study Hindi from an early age. In India there are approximately 200 million native Hindi speakers, while more than 300 million use it as their second language. There are approximately 10 million Hindi speakers outside India, primarily in Nepal.
The Devanagari script includes many more characters than western scripts such as the Roman script for the English language. While Hindi has only 12 vowels and 33 consonants, a language written in Devanagari script, such as Hindi, may include in excess of 550 characters because various phonetic characters are combined into conjunct characters. The large number of characters can make keyboard-entry of Devanagari script burdensome and complicated. Furthermore, this problem is exacerbated by the fact that many languages besides Hindi use the Devanagari script (e.g., Marathi and Sanskrit) and Devanagari-based keyboards may cater to all of them, thereby generating additional complexities.
Existing Hindi keyboard solutions typically focus on making available all or most of the 500+ characters of the Devanagari script. These comprehensive keyboards may involve complexities such as multiple virtual keyboards and multiple key-stroke characters. These complexities tend to make existing keyboard solutions difficult to learn and use. For these reasons, keyboards based, for example, on the Inscript layout tend to be difficult to use. Additionally, none of the existing keyboards have the whole script, or even most of it, visible on the keyboard.
A variety of solutions have been proposed with regard to keyboards for use with other languages such as English, Korean, Chinese, and Japanese. For example, U.S. Pat. No. 5,836,705 describes a keyboard arrangement to maximize typing speed and data entry and to ease transition from a QWERTY keyboard. This keyboard uses a layout wherein the home keys are assigned according to the frequency of use of the letters.
U.S. Pat. No. 5,945,928 describes a keyboard for the Korean Language. Keys on a keyboard are assigned a plurality of jamos (characters). Additional word processor software analyzes key sequences to resolve ambiguities and determine which characters are intended.
U.S. Pat. No. 5,999,950 describes an on-screen keyboard for the Japanese language. An array of Japanese based Kana characters are displayed. The first selection of a character key causes the display of the character in base kana form. The second consecutive selection of the same key causes the display of the character in a variant form. Subsequent consecutive selections cause the display of the character in further variant forms.
U.S. Pat. No. 6,053,647 describes a “user-friendly and efficient keyboard” for the English language. The keyboard layout places punctuation marks in the center of the keyboard with letters arranged alphabetically on either side of the punctuation marks.
U.S. Pat. No. 6,231,252 describes a downsized keyboard for use with the Japanese language. One vowel is assigned to each key of a first key group. Two consonants are assigned to each key in a second key group. An unvoiced consonant is input with a single key-pressing operation while a voiced consonant is input with a double key-pressing operation.
U.S. Pat. No. 6,275,216 describes a keyboard for entering characters for the Japanese language. One embodiment of the keyboard executes inputting of a character by zero, one, or a plurality of strokes of a code key and sequential stroke of a separator key for selecting a letter.
U.S. Pat. No. 6,281,884 describes a user-definable keyboard apparatus for use with the Chinese language. A key may correspond to one or more Chinese characters and a character may be assigned to one or more keys. The apparatus may automatically verify that a user-defined keyboard is rational by reference to a character sound grouping rules table.